1. Field of Invention
The present invention relates to an electric vehicle motor automatic transmission driving system.
2. Description of the Related Art
Electric vehicles include pure electric vehicle, hybrid electric vehicle and fuel cell electric vehicle. AC induction motor and AC permanent magnet motor are usually chosen as the driving motor of the said electric vehicles.
Both of the above two motors could make use of frequency conversion technology to achieve continuously variable transmission, therefore the variable speed transmission device is usually not necessary in industrial mechanism, and normally also not necessary for a low speed vehicle. But the above continuously variable transmission can not meet the requirement of vehicles run at high speed or vehicles have climbing capability. Variable ratio gear transmission enables a vehicle to use direct transmission or small ration transmission suitable for high speed driving and to use big ratio transmission at low speed to achieve more driving torque to improve climbing capacity.
The variable ratio gear transmission system normally includes a clutch and a gear transmission. There are three types of shifting methods for a transmission. They are sliding spur gear shifting, meshing sleeve shifting and synchronizer shifting. The sliding spur gear shifting and the meshing sleeve shifting can cause shifting shock or combination shock and introduce damage to the meshing gear. The available synchronizers utilize friction theory and enable the working surface of the meshing gear to produce friction torque to overcome the inertia torque of the meshed parts, resulting in speed increase or decrease of the gear and subsequent synchronization of the meshing gear. The disadvantages of synchronizer are that it is difficult to adjust the friction torque, it takes a long time for synchronization, the frictional surface could be damaged easily and the synchronizer device has a short life.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.